1. Field of the Invention
This invention relates to a contact structure suitable for use in a semiconductor device and a method of manufacturing the contact structure, and particularly to a structure for electrically connecting metal interconnects to a contact substrate using a barrier metal and a method of manufacturing the structure.
2. Description of the Related Art
Aluminum or an aluminum alloy is principally used in a contact as a material for forming a metal interconnect ohmic connected to an impurity diffusion region formed on a silicon substrate. In this case, a single-layer interconnect composed of aluminum or the aluminum alloy reacts with silicon in a contact diffusion region by a thermal treatment to produce alloy spikes or silicon nodules that cause an increase in contact resistance. Means such as a method of interposing a barrier metal film between a metal interconnect and an impurity diffusion region, etc. are used as countermeasures against such a problem. A titanium nitride is principally used as such a barrier metal film in view of barrier characteristics. However, the conventional titanium nitride is of a single-layer film and is utilized in crystal orientation of (111). A problem arises that a titanium nitride has weak resistance to a rapid or high-temperature thermal treatment as described in Japanese Patent Application Laid-Open No. 5-13368, for example.